One representative method of displaying a stereoscopic image by using an image display device which displays two-dimensional images is a parallax barrier system. A parallax barrier system is a system in which a zone (barrier) having alternating light-shielding portions and light-transmitting portions is provided on the front face or the rear face of an image display device, such that stereoscopy is realized by observing the display surface through the barrier.
Patent Document 1 discloses a stereoscopic image display device having a parallax barrier element on the viewer's side of a liquid crystal display panel.
FIG. 35 schematically shows an image display device 400 disclosed in Patent Document 1. As shown in FIG. 35, the image display device 400 includes, from the viewer's side, a parallax barrier element 410, a liquid crystal display panel 420, and a backlight 430. The liquid crystal display panel 420 has a construction such that a liquid crystal layer 423 is interposed between a pair of glass substrates 421 and 422 having electrodes and wiring lines for driving, thin film transistors (TFTs), color filters, and the like. On a light-entering face and a light-outgoing face of the liquid crystal display panel 420, polarizers (not shown) are respectively provided. The liquid crystal display panel 420 has a plurality of pixels, and by applying a voltage across the liquid crystal layer 423 in each pixel, the polarization state of light is changed, thus performing display.
The liquid crystal display panel 420 displays an image for the left eye in pixels indicated with the letter “left” in FIG. 35, and an image for the right eye in pixels indicated with the letter “right”. Since the parallax barrier element 410 blocks light from the liquid crystal display panel 420 in its light-shielding portions, the images from the liquid crystal display panel 420 are observed by the viewer only through the light-transmitting portions of the parallax barrier element 410. At this time, by appropriately setting the pattern and positioning of the parallax barrier element 410, the right eye of the viewer is allowed to only see the image which is displayed by the “right” pixels, and the left eye is allowed to only see the image which is displayed by the “left” pixels. Since a parallax is conferred to the images that are displayed by the “left” pixels and the “right” pixels, the viewer can experience stereoscopy.
In recent years, image display devices have been proposed which allow a plurality of viewers to view respectively different images by using a parallax barrier element. Such image display devices may also be referred to as “dual-view display devices”. Whereas a stereoscopic image display device allows the right eye and the left eye of a single viewer to view different images, a dual-view display device allows a plurality of viewers to view respectively different images. In other words, a dual-view display device separates images at positions which are farther away than in a stereoscopic image device (i.e., at greater angles). Very simply said, a dual-view display device is obtained by reducing the distance between the parallax barrier element and the pixels in a stereoscopic image display device.
An example of a dual-view display device is shown in FIG. 36. A dual-view display device 500 shown in FIG. 36 includes a parallax barrier element 510, a liquid crystal display panel 520, and a backlight 530.
The liquid crystal display panel 520 includes an active matrix substrate 521, a color filter substrate 522, and a liquid crystal layer 523 interposed therebetween. On the active matrix substrate 521, pixel electrodes and TFTs (not shown) are provided. On the color filter substrate 522, color filters 524 and a black matrix 525 are provided.
The parallax barrier element 510 includes a plurality of light-shielding portions 501 and a plurality of light-transmitting portions 502 alternating on the glass substrate 503. The parallax barrier element 510 is directly attached to the color filter substrate 522 of the liquid crystal display panel 520 via a resin layer 505, whereby the distance between the parallax barrier element 510 and the pixels (color filters 524) is reduced.
A pair of polarizers 541 and 542 are provided, on the backlight 530 side of the active matrix substrate 521 and the viewer's side of the glass substrate 503 of the parallax barrier element 510.
The liquid crystal display panel 520 has a first group of pixels for displaying a first image and a second group of pixels for displaying a second image. As the display light emitted from the first group of pixels and the display light emitted from the second group of pixels are separated by the parallax barrier element 510, a plurality of viewers are allowed to view different images.
[Patent Document 1] Japanese Laid-Open Patent Publication No. 10-268230